[CH3X4]
[CH2X4][CH2X4][CH2X4][NHX3][CH0X3](=[NH2X3+,NHX2+0])[NH2X3] 
[CH2X4][CX3](=[OX1])[NX3H2]
[CH2X4][CX3](=[OX1])[OH0-,OH]
